Neonatal Nurse Practitioner Practice Exam

In HFJV and conventional ventilation, what action increases CO2 levels?

1. Decreasing PIP

2. Decreasing rate

3. Increasing iTime

4. Increasing MAP

The correct answer is: Increasing iTime

Increasing the inspiratory time (iTime) in high-frequency jet ventilation (HFJV) and conventional ventilation can lead to increased carbon dioxide (CO2) levels in the patient. The inspiratory time determines the duration of each breath. When the inspiratory time is prolonged, it can reduce the total number of breaths delivered per minute, which in turn decreases the rate of ventilation. A critical aspect of ventilation is the balance between ventilation rate and the amount of CO2 being eliminated. If the ventilatory rate is lowered due to an increase in iTime, the effective minute ventilation decreases, potentially resulting in insufficient CO2 removal. This is particularly relevant in a scenario where the patient’s metabolic rate produces a consistent amount of CO2; if the ventilation does not keep up with the production rate, CO2 levels will rise. In summary, increasing the inspiratory time reduces the frequency of breaths and overall minute ventilation, which can lead to an elevated concentration of CO2 in the patient’s bloodstream.